Table of contents |
What is Refraction of Light? |
Causes of Refraction |
Laws of Refraction of Light |
What is Refractive Index? |
Refraction of Light in Real Life |
Applications of Refraction of Light |
What is Total Internal Reflection (TIR)? |
Formula of Total Internal Reflection |
Some Illustrations of Total Internal Reflection |
Golden Key Points |
Frequently Asked Questions |
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The bending of a ray of light as it passes from one medium to another is called refraction.
It is due to a change in the velocity of light while travelling from one medium to another.
Refraction of Light
Why do stars twinkle? Did you know that the twinkling effect of stars is due to atmospheric refraction? The starlight undergoes several refractions while reaching the Earth. This atmospheric refraction occurs in a medium of gradually changing refractive index.
Laws of refraction state that:
According to Snell's law, μ1 sin i = μ2 sin r
(i) If light passes from rarer to the denser medium:
μ1 = μR and μ2 = μD
so that,
⇒ ∠i > ∠r
In passing from rarer to a denser medium, the ray bends towards the normal.
(ii) If light passes from denser to rarer medium μ1= μD and μ2 = μR
⇒ ∠ i < ∠r
In passing from denser to rarer medium, the ray bends away from the normal.
Refractive index depends on nature and density of medium and colour of light refractive index is maximum for violet and minimum for the red light.
Refractive index, also called the index of refraction describes how fast light travels through the material.
Refractive Index is dimensionless. For a given material, the refractive index is the ratio between the speed of light in a vacuum (c) and the speed of light in the medium (v). If the refractive index for a medium is represented by n, then it is given by the following formula:
Based on the refractive index of the medium, the light ray changes its direction, or it bends at the junction separating the two media. If the light ray travels from a medium to another of a higher refractive index, it bends towards the normal, else it bends away from the normal.
When light passes from one medium to the other, the refractive index of medium 2 relative to 1 is written as 1μ2 and is defined as μ21 or 1μ2 or 1m 2
Refraction has many applications in optics and technology. A few of the prominent applications are listed below:
The phenomenon which occurs when the light rays travel from a more optically denser medium to a less optically denser medium.
Following are the two conditions of total internal reflection:
Mirage
Q.1: What do you mean by the term refraction?
Ans: Refraction is the bending of light at the surface of separation, which takes when it passes from one optical medium to another optical medium with different optical densities.
Q.2: Does reflection also take place with the refraction?
Ans: Yes, reflection also takes place with the refraction.
Q.3: For which colour of white light, is the refractive index of glass the most?
Ans: Violet colour of white light has highest refractive index.
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